雷帕霉素对糖尿病大鼠肾脏病变和VEGF及其受体表达的影响

目的 研究雷帕霉素对糖尿病大鼠早期肾脏病变的影响，探讨血管内皮生长因子（VEGF）在糖尿病肾病发病中的作用。方法 SD大鼠经链脲佐菌素（STZ，65 mg/kg）一次性腹腔注射建立糖尿病模型。建模成功后分为雷帕霉素治疗组（建模后12周开始用雷帕霉素治疗4周，n=9）、血管紧张素Ⅱ(ATⅡ)受体拮抗剂L-158809治疗组（阳性对照组，建模后12周开始用L-158809治疗4周，n=5）和糖尿病肾病组（建模12周后用等量蒸馏水灌胃4周，n=9），以未建模SD大鼠作为正常对照组（n=9）。采集各组大鼠血、尿样本和肾脏组织标本，观察和分析各组大鼠肾小球结构和功能的改变；Western blotting和免疫组织化学法检测肾脏组织VEGF及其受体VEGFR2的表达。结果 与正常对照组比较，糖尿病肾病组大鼠24 h尿白蛋白增加、内生肌酐清除率升高、肾小球体积增大、肾小球基膜增厚，两组间比较差异均有统计学意义（P<0.01）。与糖尿病肾病组比较，雷帕霉素治疗组和阳性对照组大鼠24 h尿白蛋白较少，且肾小球体积增大和基膜增厚均不明显。大鼠肾脏组织VEGF和VEGFR2表达，糖尿病肾病组明显高于正常对照组（P<0.01），雷帕霉素治疗组和阳性对照组显著低于糖尿病肾病组（P<001）。结论 雷帕霉素具有减少糖尿病肾病大鼠蛋白尿和缓解肾小球肥大和基膜增厚的作用。抑制肾脏组织VEGF和VEGFR2蛋白表达可能是雷帕霉素延缓糖尿病肾病发病的可能机制之一。

Effects of rapamycin on nephropathy of diabetic rats and expressions of vascular endothelial growth factor and its receptor

Objective To elucidate the role of vascular endothelial growth factor (VEGF) in the pathogenesis of diabetic nephropathy by investigating the effect of rapamycin on the kidney in experimental diabetic rats. Methods Diabetic rat models were established by intraperitoneal injection of streptozotocin (65 mg/kg). Twelve weeks later, all the 27 rat models were divided into rapamycin treatment group (treated by rapamycin for 4 weeks, n=9), angiotensin Ⅱ receptor antagonist, L-158809, treatment group (positive control group, treated by L-158809 for 4 weeks, n=5), and diabetic nephropathy group (intragastric administration of same amount of saline for 4 weeks, n=9). Another 9 normal SD rats were as normal control group. Blood, urine, and renal tissue samples were collected for determining changes of glomerular structure and function. Expressions of VEGF and VEGF receptor 2 (VEGFR2) in renal tissues were investigated by Western blotting and immunohistochemistry. Results Compared with normal control group, the 24 h urinary albumin increased; creatinine clearance rate rose; glomerular volume increased; and glomerular basement membrane thickened in diabetic nephropathy (P<0.01). Compared with diabetic nephropathy group, the 24 h urinary albumin decreased, and glomerular volume and glomerular basement membrane were almost same in rapamycin treatment group and positive control group. The expressions of VEGF and VEGFR2 in diabetic nephropathy group were higher than those in normal control group (P<0.01). The expressions of VEGF and VEGFR2 in rapamycin treatment group and positive control group were lower than those in diabetic nephropathy group (P<0.01). Conclusion Rapamycin can slow the progression of diabetic nephropathy by ameliorating the albuminuria and renal hypertrophy, preventing thickness of glomerular basement membrane, and reducing the expressions of VEGF and VEGR2.